From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0DFD6169AD2 for ; Wed, 29 Apr 2026 04:00:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777435252; cv=none; b=JmXwJBn2DGCLVNxDKa+O16crvCBCksEGGaqdikpzN1mT1PYXiFIsx69U+CJSwxUQVmpAi30Go9fExGwQSlSe6BvhusPHGyooOc/EUMYpH4VrB/Chey0oP3Jt0alEOlffD39BFvweW5QWAY/LMEEfjUgDt2FTP10OPpFdXBgsWy0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777435252; c=relaxed/simple; bh=Vx3l/84KLSUgSfB2eYUqxnMOVRqQuwJZr9bqN1Eazy8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ea48IGokXfTmJ1lfLr2EtFfyo1sHUAeIroOiyjdGYn+37QTAmI7Ddw5Xm1kSlYNA798o05MGl9OnNi0wohKCIx4MnswLMW6YqlIZ2d+K+3vqFctMxRBcDOVvvxRdY2rqWqzYYgNjlfSODJ/wBEzEscau1a4Lar7zKZGs5aFBDMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cJHb1f1B; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cJHb1f1B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48EDEC19425; Wed, 29 Apr 2026 04:00:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777435251; bh=Vx3l/84KLSUgSfB2eYUqxnMOVRqQuwJZr9bqN1Eazy8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cJHb1f1BdyPSs9UkF83xiwaJzn7aO4nnAQoGZx2G1vGdmV/Vppp61J9dzWgdVZ2/m xIMM1NZYiOJx2/5y/i3JB1z//RstHxQz/YyQaOfVtLSycAif7ZT/V/lYA3WxPmUF7H i+9/x4Uhct8/z501m3vi2Sj6ICsB8cJ+2AH/+zTXD8FWkzMVwrl9IDnAF70BD26opB DP47k4AfkziwtRxjijv5vvhuLRBrEIqhEG88jX6Jj/ywDfhn59RLdyGEetNffow87d C6UKEbdzoXKaFbhxIDOLLpSVjwQY/zQj/9XRNHRnNFWgfQzc7KTW2gp1o+9BUK95aE ewEUkfJwwXweA== From: Sasha Levin To: stable@vger.kernel.org Cc: Anthony Yznaga , David Hildenbrand , Pedro Falcato , "Lorenzo Stoakes (Oracle)" , Jann Horn , "Jason A. Donenfeld" , Liam Howlett , Michal Hocko , Mike Rapoport , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , Andrew Morton , Sasha Levin Subject: [PATCH 6.12.y] mm: prevent droppable mappings from being locked Date: Wed, 29 Apr 2026 00:00:48 -0400 Message-ID: <20260429040048.3342222-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026042736-vascular-rubbed-001c@gregkh> References: <2026042736-vascular-rubbed-001c@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Anthony Yznaga [ Upstream commit d239462787b072c78eb19fc1f155c3d411256282 ] Droppable mappings must not be lockable. There is a check for VMAs with VM_DROPPABLE set in mlock_fixup() along with checks for other types of unlockable VMAs which ensures this when calling mlock()/mlock2(). For mlockall(MCL_FUTURE), the check for unlockable VMAs is different. In apply_mlockall_flags(), if the flags parameter has MCL_FUTURE set, the current task's mm's default VMA flag field mm->def_flags has VM_LOCKED applied to it. VM_LOCKONFAULT is also applied if MCL_ONFAULT is also set. When these flags are set as default in this manner they are cleared in __mmap_complete() for new mappings that do not support mlock. A check for VM_DROPPABLE in __mmap_complete() is missing resulting in droppable mappings created with VM_LOCKED set. To fix this and reduce that chance of similar bugs in the future, introduce and use vma_supports_mlock(). Link: https://lkml.kernel.org/r/20260310155821.17869-1-anthony.yznaga@oracle.com Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") Signed-off-by: Anthony Yznaga Suggested-by: David Hildenbrand Acked-by: David Hildenbrand (Arm) Reviewed-by: Pedro Falcato Reviewed-by: Lorenzo Stoakes (Oracle) Tested-by: Lorenzo Stoakes (Oracle) Cc: Jann Horn Cc: Jason A. Donenfeld Cc: Liam Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton [ applied the mmap completion hunk to __mmap_region() in mm/mmap.c instead of __mmap_complete() in mm/vma.c ] Signed-off-by: Sasha Levin --- include/linux/hugetlb_inline.h | 4 ++-- mm/internal.h | 10 ++++++++++ mm/mlock.c | 10 ++++++---- mm/mmap.c | 4 +--- 4 files changed, 19 insertions(+), 9 deletions(-) diff --git a/include/linux/hugetlb_inline.h b/include/linux/hugetlb_inline.h index 0660a03d37d98..846185ea626c7 100644 --- a/include/linux/hugetlb_inline.h +++ b/include/linux/hugetlb_inline.h @@ -6,14 +6,14 @@ #include -static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma) +static inline bool is_vm_hugetlb_page(const struct vm_area_struct *vma) { return !!(vma->vm_flags & VM_HUGETLB); } #else -static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma) +static inline bool is_vm_hugetlb_page(const struct vm_area_struct *vma) { return false; } diff --git a/mm/internal.h b/mm/internal.h index b7b942767c702..3bfc1dc2d7eaf 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1015,6 +1015,16 @@ static inline struct file *maybe_unlock_mmap_for_io(struct vm_fault *vmf, } return fpin; } + +static inline bool vma_supports_mlock(const struct vm_area_struct *vma) +{ + if (vma->vm_flags & (VM_SPECIAL | VM_DROPPABLE)) + return false; + if (vma_is_dax(vma) || is_vm_hugetlb_page(vma)) + return false; + return vma != get_gate_vma(current->mm); +} + #else /* !CONFIG_MMU */ static inline void unmap_mapping_folio(struct folio *folio) { } static inline void mlock_new_folio(struct folio *folio) { } diff --git a/mm/mlock.c b/mm/mlock.c index 8c8d522efdd59..d16bf4dbd06dd 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -472,10 +472,12 @@ static int mlock_fixup(struct vma_iterator *vmi, struct vm_area_struct *vma, int ret = 0; vm_flags_t oldflags = vma->vm_flags; - if (newflags == oldflags || (oldflags & VM_SPECIAL) || - is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm) || - vma_is_dax(vma) || vma_is_secretmem(vma) || (oldflags & VM_DROPPABLE)) - /* don't set VM_LOCKED or VM_LOCKONFAULT and don't count */ + if (newflags == oldflags || vma_is_secretmem(vma) || + !vma_supports_mlock(vma)) + /* + * Don't set VM_LOCKED or VM_LOCKONFAULT and don't count. + * For secretmem, don't allow the memory to be unlocked. + */ goto out; vma = vma_modify_flags(vmi, *prev, vma, start, end, newflags); diff --git a/mm/mmap.c b/mm/mmap.c index 6183805f6f9e6..d361b1058da10 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1547,9 +1547,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, vm_stat_account(mm, vm_flags, pglen); if (vm_flags & VM_LOCKED) { - if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || - is_vm_hugetlb_page(vma) || - vma == get_gate_vma(current->mm)) + if (!vma_supports_mlock(vma)) vm_flags_clear(vma, VM_LOCKED_MASK); else mm->locked_vm += pglen; -- 2.53.0